1. Field of the Invention
The present invention relates to Digital Multimedia Broadcasting (DMB), and in particular, to an apparatus for transforming Internet Protocol (IP) format DMB data and re-transmitting the transformed DMB data to support a DMB service to a device that does not support the DMB service.
2. Description of the Related Art
Digital Multimedia Broadcasting (DMB) is a system, available on the market of Korea, used to provide a multimedia broadcasting service containing video based on Digital Audio Broadcasting (DAB: Eureka-147). DAB is a digital radio broadcasting standard used in Europe to simultaneously provide a compact disk (CD)-level high quality audio service and a data service.
FIG. 1 is a schematic configuration of a conventional DMB system.
Referring to FIG. 1, the conventional DMB system includes a DMB broadcasting device 11, a satellite/terrestrial wave 12 and a plurality of DMB receiving devices 13-1, 13-2, and 13-3. The broadcasting device 11 receives multimedia data from content providers (not shown), forms DMB data for DMB transmission from the received multimedia data, and transmits the DMB data to the satellite/terrestrial wave 12. The satellite/terrestrial wave 12 is a transfer medium through which the DMB data transmitted from the DMB broadcasting device 11 is transferred. The DMB receiving devices 13-1, 13-2, and 13-3 receive the DMB data transferred via the satellite/terrestrial wave 12 and outputs multimedia data.
The DMB broadcasting device 11 includes (1) a broadcasting center (not shown) receives produced multimedia data from content providers and forms DMB data for DMB transmission, (2) transmission facilities (not shown) for transmitting the DMB data formed by the broadcasting center, and (3) gap fillers (not shown) for re-transmitting the DMB data to remove DMB broadcasting shadow areas (areas in which DMB broadcasting signals are insufficient for reception). DMB broadcasting is well-known in the art and need not be provided in greater detail herein to describe the principles of the invention.
The DMB receiving devices 13-1, 13-2, and 13-3 include vehicle DMB terminals and portable DMB terminals.
The DMB system illustrated in FIG. 1 includes both satellite DMB (S-DMB) and terrestrial DMB (T-DMB), and thus it has been described that a transfer medium includes both a satellite and a terrestrial wave.
Generally in order to receive a DMB-based multimedia service, a user must have a DMB terminal. However, it is unreasonable for every subscriber to buy a relatively expensive DMB terminal. However, DBM interface apparatuses and methods using an IP method are being developed whereby a DMB service can be received using widely used existing devices for processing packet type data. For example, a wireless local area network (WLAN) terminal, a Bluetooth terminal, or a 3rd generation (3G) terminal supports a mobile network.
However, these DBM interface apparatuses and methods using an IP method are adversely effected by the errors that may occur in the medium. For example, if many errors occur in an occupied wireless channel, a user cannot receive a broadcasting service corresponding to a desired level according to a characteristic of the DBM interface in which continuous data transmission is important.
When data is transmitted using a wireless channel, it is important that the data is transmitted with packet length having the best transmission efficiency for the transmitting channel according to a characteristic of a wireless channel environment. In terms of transmission efficiency, the longer the packet length, the better. However, in the wireless channel environment in which many errors occur in a channel, as a probability of transmission failure increases as the packet length increases. Thus, it is necessary to select a proper packet length in the selected wireless channel environment. In order to effectively interface an image signal with a wireless network, it is important to encode the image signal in a manner suitable for a wireless channel is required.